Add missing include to resolve LifetimeIntrinsic

Author: Icohedron

llvm/lib/Target/DirectX/DXILPrepare.cpp

@@ -24,6 +24,7 @@
 #include "llvm/IR/AttributeMask.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Instruction.h"
+#include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Module.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"